A conventional Wideband Code Division Multiple Access (WCDMA) is a circuit based system that transmits control information such as a signaling message from a base station to a terminal using a downlink dedicated channel. A long term evolution (LTE) system was introduced as a packet-based system and has been standardized for providing various packet services, and there have been many researches in progress for finding a method for effectively and variably using radio resources for the LTE system.
The long term evolution (LTE) system is a technology that realizes a high-speed packet-based communication, for example, about 100 Mbps. It is expected that the LTE system will be commercialized by around 2010. An Orthogonal Frequency Division Multiplexing Access (OFDMA) has been considered to be used for the LTE system. Unlike a Code Division Multiple Access (CDMA) that distinguishes radio resources of each terminal by allocating codes, the OFDMA system has two dimensional radio resources distinguished by a frequency and a time. That is, the OFDMA system transmits and receives radio resources constituted of time and frequency for uplink physical channel and downlink physical channel. Also, the OFDMA system uses radio resource blocks divided by a transmission time interval (TTI) as a transmission period and a subcarrier group. A radio frame constituting such radio resources is formed of 0.5 millisecond slots or TTIs. Therefore, one radio frame is formed of 20 slots in case of a 10-millisecond radio frame.
Unlike a circuit system that dedicatedly allocates radio resources to terminals, the packet-based LTE system allows terminals to share radio resources to transmit a packet service data. The LTE system allocates radio resources according to a radio channel condition of a terminal, which dynamically changes according to whether the necessity of data transmission and according to a time. Therefore, the LTE system needs a method for providing uplink control information to various terminals through a radio resource in order to enable each of terminals to discriminate radio resources allocated to itself from radio resources allocated to the others, access, and modulate the allocated radio resource according to a cycle of allocating a radio resource. Also, the LTE system needs a method for forming an uplink control information to variably and flexibly use physical layer radio resource and a method for transmitting the uplink control information.
In order to satisfy such a demand, there was a discussion in progress to classify radio resources into a local allocated radio resource and a distributed allocated radio resource for adaptively allocating and using radio resources corresponding to a wireless environment. In order to effectively allocate these two radio resources, it has been considered to transmit the control information such as a signaling message using a control channel that is shared with a plurality of terminals instead of using a dedicated control channel like the conventional WCDMA and to transmit some of control information using radio resources allocated to each of terminals.
That is, there is a demand for developing a method for effectively forming uplink control information such as an uplink signaling message using a downlink from a base station to a terminal and transmitting the uplink control information with minimum radio resource occupied, thereby improving the usability of limited radio resources.